


Paradigm shift

by Caitycaterpillar



Category: Ao no Exorcist | Blue Exorcist
Genre: Alternate Universe- How to Train Your Dragon, Gen, and no vikings, but except with exorcists, or dragons, so it basically httyd
Language: English
Status: In-Progress
Published: 2016-08-18
Updated: 2016-08-18
Packaged: 2018-08-09 13:57:11
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,178
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7804474
Author URL: https://archiveofourown.org/users/Caitycaterpillar/pseuds/Caitycaterpillar
Summary: <blockquote class="userstuff">
              <p>Killing the demon in front of him should be like killing a bug. He should be able to pull the trigger and then walk away like nothing ever happened. He shouldn't feel guilty about what he was about to do. He shouldn't!</p><p>(Or- the one where Yukio fails to kill a demon and it turns out to be more of a hassle expected.)</p>
            </blockquote>





	Paradigm shift

**Author's Note:**

> So this is basically a kinda sorta fusion of httyd and AoE. This baby has been bouncing around my head for weeks and this is basically what spewed out when I finally got around to typing it out.

The world was on fire.

The sky was dark and the sun had disappeared hours ago but the bright flames of the burning buildings lit up the area well enough to make it seem as if there was a spotlight shining down on them. The sound of crackling fire and crumbling buildings filled the air as people rushed to evacuate.

A large explosion shook the ground and Yukio put a hand onto a nearby wall to steady himself. He only had a brief warning of _'Get down!'_ before the wall shuddered and cracked down the middle. Shrapnel flew over his head in little clumps and hot air tickled his neck.

Deciding that knowing what was going on was worth the risk Yukio peaked through the newly made gap and groaned. What a nightmare! A full scale raid and he didn't have any bullet belts or grenades on him, only a few cartridges. Not nearly enough to keep him safe the entire night.

Yukio leaned back and took a second to centre himself. He had a gun that settled awkwardly in the center of his palm, it was too big and he couldn't quite find any comfortable way to hold it. He doubted that he would be able to shoot anything at all with it but it was better to be arms with _something_ than to go out in a raid completely unarmed.

Yukio took a deep breath. He could do this. His dorm wasn't all that far from here and he was sure that he could make the trip without crossing paths with a demon. Stepping out Yukio ducked under an airborne demon and began to make his way down the path.

A weight latched onto his coat. Yukio's heart dropped.

“Incoming!” A woman shouted and Yukio only had enough time to turn before he was doused with hot Holy Water. A hiss slipped past his lips from the heat but he didn't complain. It was common practice that an exorcist would have Holy Water poured over them before going into major battle. The wet clothing was uncomfortable but everyone knew that it was better to have Holy Water on their side than to deal with the demons dry.

The hob-goblin that had been clinging to the back of his shirt screeched as the water hit and then burst into a thousand pieces.

Demons, Yukio thought as he wiped away the black mud, were disgusting creatures. They normally came in terrifying, often rotting, packaging and had this annoying habit of attacking people for no apparent reason. They also had an unnatural attraction to any Vatican Headquarters. Yukio wasn't sure why but every demon seemed to take a sort of vindictive glee over destroying the city.

Most people would leave when their homes were destroyed by demonic creatures. Not them though, they were exorcists. It was hardly uncommon to find exorcists with more than one house or room on opposite ends of the city. Living in a city full prone to demon attacks was just another way of life here.

The leader of this branch of the True Cross thought that living in an area where demons practically flocked to was good training for trainee exorcists and to a certain extent, he was right. True Cross City was the ultimate training destination for anyone who wanted to brush up on their skills or, for those who hadn't any talents and needed some, to develop a few.

Something caught the back of Yukio's shirt and harshly pulled him backwards just in time to save him from being bowled over by an absolutely _huge_ Hob-goblin. His moment of reflection having distracted him and subsequently, nearly gotten him killed.

“Now, Yukio.” the paladin chastised him and waved a finger in his face, “You really shouldn't be running around here without supervision. It's quite busy tonight. You haven't even started training yet, how were you supposed to protect yourself?”

“Who's fault is it that I haven't started training?” Yukio scowled and earned himself a laugh from the paladin. “And anyway, I was on my way back to the dorms when the raid started. Unfortunately for me, I keep getting held up.”

“All right, all right I can take a hint. Hurry on home and don't forget to activate the wards.” The man shoved Yukio in the direction of the dorms and then turned to his student. The woman had been merrily slicing away at anything that had come close to the chatting pair.

“What are we dealing with tonight?” the Paladin asked as he pulled the cap off a grenade. The bomb landed neatly in a group of demons. They screamed when it exploded.

“Uhh, lemme see.” The woman in the bikini top waved her sword in the air as she mentally ticked off each of the demons that had been spotted, “Hob-goblins, ghouls, naga, some leapers. Oh! A couple bariyon rolled down the hill and squashed some poor sap some ways down.”

“Any of the Demon Kings?”

“None yet.” The Paladin nodded, looking pleased at that.

“Good,” he snorted, “hopefully we won't have to rebuild any major buildings this time.” He turned and commanded a new group of exorcists.

-o0o-

 Yukio huffed, slightly out of breath as he closed the door to the dorms and swiped the wards active again. He knew he really should be staying safe indoors but this was probably the only chance he was going to have at proving himself before school started again. There was absolutely _no way_ he was going to begin cram school as the only trainee there without a scrap of experience on the field, protective fathers or no.

And anyway, he had a plan. A very good plan that was going to leave everyone speechless.

Racing back to the main road Yukio couldn't help but feel a stab of disappointment. It looked as if most of the demons had already been exorcised. All that was really left was the higher class demons that had a resistance to most types of bullets and Holy Waters. A shadow passed overhead and Yukio felt a shiver of excitement. This was it!

Only... it wasn't.

A flash of red glittered in the corner of his eye and Yukio hardly had any time to react before the demon died in a splash of black dust.

“Oi, oi. Look-y what we have here~” a familiar voice drawled and Yukio groaned. _Noo_ , why did it have to be _her_ that found him? Could it had not been anyone else?

“Don't you have anyone else to bother, miss Shura? I'm sure that father would love your company.”

Shura chuckled as she sliced open a ghoul that had gotten too close, “Careful, Yukio. If I didn't know any better, I'd think ya didn't want me around anymore! And besides, who's going to look after poor little Yukio while daddy's not around to protect him?”

Yukio fumed. It wasn't his fault that he hadn't been allowed into training yet! And it didn't matter anyway, he was going to be joining the paiges soon for training whether his father said so or not. The bespectacled teen wished dearly that he could tell his father's obnoxious apprentice this as well as the fact that he would love it if she would just _leave him alone_ when...

The sky flashed blue. A horrible bright blue that made chills run down the spines of everyone present.

“Demon King, take cover!” the speaker system crackled. Yukio and Shura hit the ground. A moment later a shadow streaked past them and the world exploded behind it.

“ _Shit._ ” Shura hissed and pulled debris out of her hair, “The little fucker always manages to get us, eh Moley? Moley? Hey! _Yukio!_ ”

Yukio almost didn't hear her, he had long gotten up and was running after the shrinking shadow of the demon.

“I'm going to go test something out!” he shouted over his shoulder and ignored all else that the feisty woman shouted at him. He already knew what she was going to say so did it really matter that he didn't listen?

People didn't like it when he tested out his new weapons out in the field. They always seemed to react in unexpected ways and though Yukio found the different reactions fascinating, the rest of the exorcists didn't share his sentiments. They didn't share his excitement at creating a more effective bullet than expected. They said to leave the experimenting to R&D. They just didn't get it. They didn't get that to Yukio taking down the Demon Kings was his dream.

To take down a Demon King would be to make the world a safer place.

Demon Kings, the one Yukio was chasing in particular, were demons that the Order of the True Cross didn't have much info on. They never stole goods, never initiated fights with exorcists and more importantly, were never seen. They were the brains of the operation and normally hid behind hordes and hordes of their kin. With this King all the warming you got was a flash of blue light before the world burst into flames.

Though, as devastating as the blue fire was, this King was actually still the most preferable of the lot. He was practically the only one that people actually had a warning that he was going to attack as well as the only one that didn't summon armies of demons to annoy people. Yukio wasn't actually sure if the Fire King _could_ actually call other demons.

He wasn't complaining though. That couple seconds that the King's fires lit the streets were used to the fullest and take cover. The other Demon Kings weren't that kind. There was often no warning before a devastating earthquake hit or the air erupted in poisonous spores.

Somewhere behind Yukio something exploded and hot air rushed past him, adding to his momentum and whipping his hair. Yukio forced himself to go faster. His window of opportunity was growing smaller.

The viewing platform came into view and the young exorcist could almost _taste_ victory.

As quickly as he could, Yukio pulled out a metal cross on a chain and strung it through his fingers and started to chant. He had recently found an old tomb that spoke of sealing a demon's power and was sure that it was going to work. Unfortunately, the demon had to be in sight for the spell to work so he had to wait. All he needed was for the King of Fire to give him one good flash. One good wave of flames that would light up the many buildings of True Cross and give him a glimpse of what he was dealing with. All he needed was a peak and it would all be over.

In the corner of his eye Yukio caught a flash of blue and swivelled to stare directly in the the blaze. A figure shot out of the fire and Yukio shouted the last verse of his chant.

There was a roar of anger as the spell took effect mid jump and the King screeched before rushing off in the direction of the woods near the Exorcist Shop. Not towards the edge of the city where the survivors usually run off to once the raids are completed.

Yukio stood on the platform, dazed, for a second before a bubble of excitement rippled through his chest. He'd done it. He'd hit a Demon King!

-o0o-

It must have been Yukio's lucky day. Not only did he shoot a Demon King straight out of the sky but he also managed to hit the beast at such an angle that the unholy thing fell within a warded area! All he needed to do was say the activation phrase and touch the runes and the beast would be trapped! The ward that normally repelled the disgusting beasts would work just as well as a cage. Now, even if it managed to get passed him, the demon would never be able to leave this little piece of forest it fell into.

Looking at the lump of dark material laying well within the edges of the 'safe-zone' Yukio spared a moment to shift his bazooka in front of him. The weapon didn't have any lethal bullets within it, just a net, and Yukio was starting to wonder if that was such a great idea. Being unarmed in front of a demon meant death after all.

The beast stirred and the young exorcist pulled the trigger in alarm. The net exploded from the barrel with a tremendous force and collided with the demon making it skid and roll a couple meters back. It groaned but didn't move after that and Yukio took a moment to center himself. He had to calm his frantically beating heart before stepping forward.

 _'This is it.'_ Yukio thought. He was finally going to start clearing the world of the demon filth that plagued it. The too large, uncomfortable gun settled back into Yukio's grip and he silently loaded it with his special AAA-grade Holy Water bullets.

The demon's appearance came into view and Yukio's thought process stuttered to a halt. _This_ was the demon he had been hunting? Where was the rotting flesh? The disproportionally sized body parts? The god-awful stink that normally accompanied demons?

Really, the demon actually looked like it could pass for a human and that fact disturbed Yukio down to his very bones.

The demon had navy hair, black clothing and tan skin that was covered in scratches from the fall. There were five fingers easily spotted covered in black fingerless gloves, a set of eyebrows, eyes and ears and _one_ nose and mouth. There were no extra (or missing) arms and legs. The only thing that Yukio could say told him that the thing laying on the ground in front of him was a demon was its eyes.

Unnaturally blue with slit _red_ irises. It sent shivers down Yukio's spine.

The demon's glare was practically toxic and its gaze burned on his skin. It glared at Yukio and he felt as if he was drowning, as if he had done something absolutely _horrible_ and deserved to die. Dimly, Yukio remembered that he read something about the eyes of a demon; that they were hypnotic. The demon's lip pulled slightly. Yukio caught sight of a sharp incisor and the spell was broken.

There was a moment of a frantic scramble where Yukio finally remembered the gun in his hand and raided it to aim at the demon's head. It flinched slightly before ignoring the gun to glare defiantly at Yukio.

This time, Yukio made sure to not look it in the eye again.

His finger tightened on the trigger, the muscles in his arm feeling uncomfortably tight as he pointed the weapon at the demon’s head. His arm creaking with stiffness and his heart beating frantically.

“Shoot.”

The surprisingly smooth voice came unexpectedly and Yukio jolted in surprise. He didn't know that demons could speak any human languages. They barely held enough intelligence to speak to their own never mind other species.

“What are you waiting for?” the Fire King said, sounding forced, “Shoot.”

Uncertainty flooded his being and Yukio almost lowered his gun. He didn't know what to do now. He wasn't sure if he could kill the demon now that he knew it was sentient; it felt wrong.

Every since he was young, he was told that it was _okay_ to kill demons because they weren't really alive to begin with. They had no sense of self and could hardly think for themselves, hence the need to follow their Kings. The Kings were bigger and more powerful and so _surely_ where they go food would be plentiful, enough to feed a king in fact.

The demons were just creatures possessing animals, using their hosts to complete tasks and attack exorcists. They hardly felt pain too, so putting a bullet in their skulls wasn't _really_ killing them; it was more like delaying them and forcing them back into their own realm.

Yukio could still remember the times when he was little and had cried over the death of demons because he had heard in church that it was wrong to kill. A passing exorcist had come to speak to him then. Saying that it was okay and that it was more like stepping on an insect, a cockroach, than killing an animal. It may be disgusting and messy at the time but really there wasn't any need to concern yourself over it because there were a thousand more where the previous one came from.

Killing the demon in front of him should be like killing a bug. He should be able to pull the trigger and then walk away like nothing ever happened. He shouldn't feel guilty about what he was about to do. He shouldn't!

But he did.

“You attacked our city and have killed many exorcists in the process.” he said, trying to convince himself of the Fire King's guilt. It was easier to push away his feelings if he knew the demon was wrong. That it had to die. The demon's face twisted in anger.

“I haven't killed anyone.” it snarled and Yukio's hand shook. The demon King spared a moment to watch his shaking hand before sighing, anger draining from his features. Its head hit the ground with a thump.

“But if shooting me would make you feel better,” it closed its eyes, “then go ahead and shoot.”

Yukio felt like he would be torn in half with uncertainty. He had no idea what he was supposed to do. The fact that this demon was totally at his mercy and had resigned itself to die at his gun made him feel a little guilty. He would have preferred it if the damn thing fought him and died in the scuffle.

“Why did you attack True Cross?” he found himself asking. The demon's ear twitched and its tail wound and unwound in an agitated manner but it didn't make a move to open its eyes or even get up.

“It was either I come or the Earth King would pay you a visit today.”

Yukio lowered his gun and used his free hand to scrub at his eyes. Damn it all, the uncertainty was _eating_ him now. How was he supposed to kill the Fire King now when he knew that he had saved them from having to deal with one of the more blood thirsty Kings? His mind raced as he tried to come up with a better plan with what to do with the creature in front of him.

Finally deciding what to do Yukio took his finger off the trigger, pulled the cartilage out of his gun and swapped it for another. He took three seconds to aim and then another three to fire. The bullet hit the demon and the beast fell still.

-o0o-

Yukio went home that night with his heart in turmoil.

His whole world had practically been tipped on its head and it was all that demon's fault. How dare it! Telling Yukio all that stuff and telling him that the Earth King would have come in his place? Just who did it think it was? The whole situation just pissed him off.

The door to his private dorm hit the wall behind it with a bang and Yukio cringed at the noise before switching on the light. The person sitting in the chair at his desk nearly gave him a heart attack.

“Yukio!” the Paladin greeted. “So nice of you to finally join us! Now, tell me, whatever happened to staying safe behind the wards?”

Yukio cringed but stayed silent.

“ _Ahh_.” the Paladin hummed and nodded his head slowly, “I see, I see. Indeed that is a perfect reason as to why you deliberately went against my orders.”

Yukio cringed even further when the older man's eyes narrowed.

“Tell me, Yukio-kun, for what reasons did you disobey a direct order and rush off on your own? Shura tells me that you raced off in the direction of a demon King but surely she was mistaken, no?”

Briefly Yukio wondered if he would get away with shooting Shura in the head before he shook away those thought and focussed on the matter at hand.

“It wasn't as if I was planning on disobeying them.” he started strong before losing momentum halfway, “It was just... I... wanted to try something new. Against a demon King.”

The Paladin's face went blank and Yukio panicked.

“It’s okay! It worked! I actually got it!-”

“Yukio.”

“Now all you have to do is gather a team-”

“Yukio!”

“and take them over to the area around the exorcist shop and-”

“ _YUKIO!”_

Shocked the teen fell silent and stared at the other man. The Paladin sighed once and swiped a hand over his face.

“Its times like this where I worry that you're not ready to become an exorcist yet.” he said and it was like a punch to Yukio's heart.

“W-what?” the teen whispered before exploding. “No! You can't do that! I've been training! I've studied all the texts you gave me! I even put up with that floozy you call 'apprentice'!”

The paladin scowled. “Yes, you studied and you practised but did you put any of the things you learnt to good use?”

“Yes I did!”

The Paladin sighed again, this one much more forceful than the last. “Okay, fine. One more chance. I'll give you one more chance to prove to me that you're serious about this okay? But after that, one more outburst and I'm sending you to the Monastery. Do we have a deal?”

Yukio forced himself to settle down. “You're not even listening to what I have to say.” he told the man but was ultimately ignored.

“I _said_ , 'do we have a deal'?” Yukio swallowed the hurt he felt and looked off to the side.

“Yes,” he said, “we have a deal.”

“Good.” the Paladin nodded and got up off the chair. The man stared at the miserable teen for a moment before walking forward and engulfing the younger in an all-encompassing hug. “You _know_ I'm only doing this because I worry, Yukio.”

Yukio felt his heart twist uncomfortably and turned into the hug, burying his head into the space between shoulder and neck.

“I know.”

The man tightened his hold on the quivering teen for a second before pulling back. He smiled a bit and moved to righten Yukio's glasses.

“Right, I think it's time for bed. You have a full day tomorrow what with classes in the morning and cram school in the evening. Better get all the hours you can, it’s going to be a long day.”

Yukio nodded and briefly looked at his bed. Sleeping actually sounded really good after the emotional roller-coaster ride he had been put through today.

“Yeah, that sounds like a plan.” he told the man. “Are you going to be in the office when I get out from class? Who am I supposed to go to for my Key?”

“I'll come around and drop it off just before class, don't worry.”

Yukio sighed and then moved aside, allowing the older man to pass by. “Okay then I'll see you later then.”

“Later.” the man agreed. “Night Yukio.”

The teen smiled weakly, one hand on the door. “Night, dad.”

Yukio groaned and leaned his head on the door and he listened to his father's retreating footsteps. As much as he loved the man, the Paladin had just never been very keen on the idea of letting his only son become an exorcist. Yukio could understand it a little but really. His father was the Paladin! The greatest knight in the order! Was it really that surprising that he wanted to make him proud? Yukio threw himself at his bed, ready to end this horrible day once and for all.

“Ouch!”

But unfortunately the universe wasn't done with him yet.

Yukio lifted his stomach of the bed slightly and rummaged through his pocked with one hand. Something warm and much larger than anticipated brushed his fingers and Yukio sat up with a jolt. The cross charm that he had used in his earlier spell was brought out and he stared at it in shock.

It was about three times larger than it was before he used it and coloured a bright blue where before it was grey.

Yukio shifted the cross pendant, because it wasn't really a _charm_ any more, onto his sheets and wondered what the hell was going on. When he had bought the cross, the thing had been just smaller than his thumb. _Now_ however, it was the size of its palm.

It also was the same colour blue of those unholy blue flames and just about as warm as an overheating computer but those were the least of Yukio's problems.

After all, its not just everyday that you carry around the sealed power of a demon King in your pocket.

 


End file.
